Compound for the automatic removal of copper from ordnance



ALAIN ELIE ALFRED DAGORY, OF BOIS COLOM'BES, FRANCE.

COMIOUND FOR THE AUTOMATIC REMOVAL OF COPPER FROM ORDN'ANCE.

Specification of Letters Patent.

Patented J an. 18, 1921.

No Drawing. Original application filed July 9, 1920, Serial No. 395,080. Divided and this application filed September 30, 1920. Serial No. 413,888.

nue Robert Bain No. 8, France, have invented certain new and useful Improvements in and Relating to a Compound for the Automatic Removal of Copper from Ordnance, of which the following is a complete specification.

This invention relates to a compound for ailtomatically freeing guns of all calibers from the copper which is deposited, during the firing, in the interior of the bore.

. After'a certain number of shots have been fired, especially when they are fired rapidly, and when guns are employed having grooves the pitch of which is not progressive, there are produced in the grooves and on the ribs between them, deposits of copper which are derived from the driving bands of the shells. This metal adheres very strongly to the walls of the bore of the gun and the effect thereof is to interfere with the function of the grooves and consequently act prejudicially on the accuracy of the firing. It also accelerates in an appreciable manner the wear of the guns by increasing the strain on the grooves and it may go'so far as to cause the bursting of the gun.

The operation which consists in removing this copper, and is ordinarily called decoppering, takes place rapidly and automatically by utilizing the compound which constitutes the subject matter of the present specification.

The invention is based on 3 the affinit which tin when in a state of fusion has for copper and on the property which these two metals possess of forming together compounds of relatively low melting point and in all cases lower than the temperature attained by the powder gases during the passage of the projectile through the bore of the gun.

The compound is composed of tin and I lead and is placed in the bore of the gun duringthe firing.

By way of example one may be cited which gives good results and consists of the following proportions viz. per cent. of Sn (tin) and 45 per cent. of Pb (lead).

The metallic composition may be introduced into the shell or cartridge case, or the alloy may be placed either in .the powder charge or immediately in front of it. It

maybe employed in any form. e. g. washers, past ls, powder, granules, etc. In this case it. is the extremely rapid movements of the powder gases which bring about the contact between the alloy in its liquid or volatilized state and the copper deposited on the bore of the gun.

As soon as the powder gases have made their actioni felt the alloy in question becomes fused. The tin and the lead, the meltin points of which are 232 C. and 325 respectively, present in fact the property of forming compounds of a disaggregation point which varies according to the .proportlons of one or the other metal, and the minimum melting point of which corresponding to the eutectic mixture of tin and lead is 187 C.

If it be considered that the temperature attained in the bore of the gun by the powder gases is of the order of from 2000 C. to 2200. C. it will be readily understood that in the presence of such an excess of temperature, the disaggregation of the composition of tin and lead takes place almost instantaneously.

The tin and the lead, being reduced to the liquid state are projected by the pushing due to the gases produced by the combustion of the powder along the walls of the bore of thegun, in the form of fine small drops which are brought into contact with the copper. This latter metal then forms with the tin fusible alloys as has been explained above, the copper and the tin giving rise in fact to the formation of a eutectic mixture composed of 97 per cent. of tin and 3 per cent. of copper the melting point of which is 220 C.

" formed are thus certainly realized.

As regards the lead, it does not combine with the copper but under the circumstances I it plays the part of a lubricant. Its adhesive power is not comparable to that of the copper, and it disappears on the passage of succeeding shells along with the fusible compounds of tin and copper.

It goes without saying that the propor- I the nature of the fusible metals employed.

Finally, experience has proved that the figure of 10 grammes of alloy given as a basis in the specification of the principal patent for use with the 75 mm. shell, as in no. Way

absolute. It may be considerably reduced.

What I claim is:

1. A compound for use in the removal of copper from the bore of ordnance, consisting of an explosive material and an amalgamating element.

2. A compound for use in the removal of copper from the bore of ordnance, consisting of an explosive material and tin.

3. A compound for use in the removal of copper from the bore of ordnance, consisting 4. A compound for use in the removal of copper from the bore of ordnance, consisting of an explosive material and an amalgamating element in approximately circular form. 5. A compound for use in' the removal of copper from the bore of ordnance, consisting of powder and an 'amalgamating element mixed therewith.

6. A compound for use in the removal of copper from the bore of ordnance, consisting of an explosive material and an amalgamating element at one end thereof.

In testimony whereof I have hereunto set my hand at Paris this 8th day of September 1920.

ALAIN. ELIE ALFRED DAGORY. 

